Ultrashort wave oscillation generator circuit



Feb. 22, 1938. H. o. PETERSON ULTRASHORT WAVE OSCILLATION GENERATORCIRCUIT Filed Nov. 8, 1934 2 Sheets-Sheet l JIICWPHO/YE INVENTOR H.O.PETERSON BY Q)- ATTORNEY Feb. 22," 1938. H. o. PETERSON 2,108,990

ULTRASHORT WAVE OSCILLATION GENERATOR CIRCUIT Fi led Nov. 8, 1934 2Sheets-Sheet 2 +4.0. PETERSON BY guy-1M ATTbRNEY Patented Feb. 22, 1938ULTRASHORT WAVE OSCILLATION GENER- ATOR CIRCUIT Harold Olaf Peterson,Riverhead, N. Y., assignor to Radio Corporation of America, acorporation of Delaware Application November 8, 1934, Serial No. 751,984

masts Claims.

This invention relates to a method of and apparatus for generatingultrashort wave oscillations, and in particular to a circuit arrangementwherein the principal elements of an oscillation generator tubeconstitute the conductors of a concentric transmission line.

Heretofore it has been the practice to generate ultrashort waveoscillations with circuits employing a tube and an associatedoscillatory circuit connected to the elements of the tube but locatedexternally of the tube envelope. One common form of such an oscillatorycircuit is a transmission line operating with standing waves upon it.

It is known that if a conventional type of tube is connected to such atransmission line constrtuting an oscillatory circuit, that thecapacities of the elements within the tube will cause a change ofconstants in the transmission line which might be sufficientlydetrimental to prevent the circuit from functioning as a truetransmission line. One of the objects of the present invention is toprovide an improved form of tube, so constructed that the elementsthemselves form a uniform transmission line, and this is achieved, inthe preferred form of the present invention, by the provision ofcylindrical elements constructed as concentric transmission lines onwhich standing waves are developed.

Although elements of this form are preferred, it is to be distinctlyunderstood that the invention is not limited thereto, since other shapesof transmission line may also be employed.

A better understanding of the invention may be had by referring tothefollowing detailed description, which is accompanied by drawings whereinFigs. 1-4, inclusive, show different embcdiments of the invention, andFig. 1a shows a cross sectional view of the tube of Fig. 1.

Referring to Fig. 1 in more detail, there is shown a completetransmitting circuit arrangement employing a tube whose elements areconstructed to form a transmission line one-quarter of a wave lengthlong. In this tube, the elements of which are shown located within anevacuated envelope H), which may be of glass or other suitable material,there is shown a concentric transmission line which is one-quarter of awave length long comprising an outer anode 4 and an inner grid 3, thelatter of which is a perforated continuation of the inside conductor ofthe concentric transmission line. The outer conductor or anode 4 isconnected at one end of the line through a capacity to the cathode 2,which is supplied with. heating current by transformer I in circuit withsource of energy II, and at the other end thereof to the insideconductor through another by-pass capacity. Numeral 5 indicates theinsulating dielectric of the capacities at both ends of the line. Itwill thus be seen that the grid 3 is at the high potential end of aone-quarter wave length resonator, the grid element 3 being wellshielded by the anode element 4.

It is preferred to operate the tube as a Barkhausen type oscillator,wherein the grid is main tained at a high positive potential withrespect to the cathode and the anode at a much lower potential, wherebypendulum motion of electrons emitted by the cathode is obtained aboutthe grid. If desired, a constant magnetic field, such as is provided bycoil 8 and unidirectional source of potential l4, may be employed toreduce the flow of electrons along the length of the conductor. For thispurpose, unidirectional source of potential l2 supplies the grid with ahigh positive potential and source is supplies the anode with a muchlower positive potential, although it will be understood that the anodemay be at zero or negative potential with respect to the cathode.

If it is desired to modulate the oscillations, there maybe provided amodulation microphone 'l which impresses modulating currents upon anamplifier 6, in turn connected through a transformer 24 with the anodeand cathode of the tube. Any suitable utilization circuit, such as anantenna 9, may comprise the output of the circuit and be connected tothe inner'conductor of the concentric line, as shown.

Fig. 1a is a cross sectional view of the tube along the lines A, A.

Fig. 2 shows another embodiment of the invention, wherein the outsideconductor of the concentric transmission line is made tobe the cathode,electron emission in this case being obtained at desired points, hereindesignated 2, 2, spaced onehalf wave length apart, by coating the insideof the outside conductor with suitable electron emitting material andsupplying concentrated heat at the desired points through transformersl, I. The inside conductor 3 is the grid, which is maintained positivewith respect to the cathode and is shown constructed in the form of aperforated cylinder. In this embodiment electrons.

nodal points of this transmission line is herein obtained by means ofconstant magnetic field coils 8. The potential curve is shown by the'dotand-dash lines. The outputcircuits herein comprise dipole antennael5, l5 connected with transmission lines l6, IE to the potential nodalpoints on the grids 3. A reflector ll serves to concentrate theradiation from the dipoles in any desired direction.

It will be noted that the magnetic fields are so polarized as toconcentrate the flow of electrons to restricted sections of the lengthof the tube. Every other antenna feeder is reversed and so-connectedthat the antennae l5, l5 radiate cumulatively in the directionperpendicular to the axis of the reflector I1.

Fig. 3 shows still a third embodiment wherein the outer conductor hasits inside coated with suitable electron emitting material at a desiredpoint which is chosen to give proper loading of the one -quarter wavelength resonator, as shown in the drawings. In this embodiment theconcentric transmission line has an overall length of one-quarter wavelength, and the distances at and b are so chosen as to give the properloading. 1 V

Fig. 4 shows a still further modification utilizing a magnet yoke IT.The inside conductor of the concentric transmission line in thisinstance may comprise some magnetic material, such as nickel, in whichcasea highly concentrated magnetic field may be produced perpendicularto the axis of the concentric transmission line. The electron emittingmaterial is herein shown at the top on the inside of the outer elements,the output being shown obtained from a tap at the bottom of the tubeover lead 3. The magnetic field is so arranged as to concentrate theflow of electrons to a restricted section of the length of the tube. V

7 It will be understood, of course, that the invention is not limited tothe precise details shown since various modifications may be 'made inthe structure of the elements without departing from the spirit andscope of the appended claims, nor is the invention limited to thepositive grid type of oscillation, inasmuch as the principles may alsobe applied in the type of oscillation circuit wherein the anode is madepositive and the grid negative with respect to the cathode. 7

By the term multiple of one-quarter wavelengt used in the appendedclaims, is meant any multiple including one.

What is claimed is: 7

1. An ultrashort wave oscillation generator circuit comprising amulti-electrode electron discharge device having within its envelope anoscillatory circuit in the form of a concentric transmission line havinginner and outer conductors of a length equal to a multiple of onequarterof the length of the operating wave, said conductors comprisingelectrodes of said devices, said inner conductor comprising a perforatedgrid over at least a portion of its length, said outer conductor havingthat part of its inside portion opposite the perforated grid coated withan electron einissive material, a source of energy for heating saidelectron emissive material for liberating electrons, means for applyingsuitable polarizing potentials to the electrodes of said device, and autilization circuit coupled. to said inner conductor.

2. An ultrashort wave oscillation generator circuit comprising amulti-electrode electron discharge device having within its envelope anoscillatory circuit in the form of a concentric transmission line havinginner and outer conductors of a length substantially a multiple ofone-quarter of the lengthof the operating wave, said conductorscomprising electrodes of said devices, said inner conductor comprising aperforated grid over at least a portion of the length of said conductor,said outer conductor having its inside coated with an electron emittingmaterial at predetermined points throughout its length, said pointsbeing opposite perforations on said grid whereby the emission ofelectrons from said material enables said electrons to pass through theperforations in said grid, means for heating said electron emissivematerial and for applying suitable polarizing potentials to saidelectrodes, and means for obtaining oscillations from said devicecomprising a utilization circuit connected to a voltage nodal point onsaid grid.

3. A system in accordance with claim 2, characterized in this that saidpredetermined points on said outer conductor are spaced apart an evenmultiple of one-quarter the length of the operating wave, and saidutilization circuit, comprises two antennae each connected to a voltagenodal point on said grid.

4. An ultrashort wave length oscillation generator circuit comprising amulti-electrode electron discharge device having within its envelope anoscillatory circuit in the form of a concentric transmission line havinginner and outer conductors, said inner conductor comprising a perforatedgrid and said outer conductor comprising an anode, a source of electronslocated within said grid, said anode: being capacitively coupled to saidgrid at one end of said line and capacitively coupled to said source atthe other end of said line, means for maintaining said grid at a highpositive potential relative to said source and anode, and means forproducing a magnetic field within the length of said concentrictransmission line.

5. A circuit in accordance with claim 4, includof a length substantiallyone-quarter of the.

length of the operating Wave and which are capacitively coupled togetherat one of their ends, said outer conductor comprising a cathode,

and said inner conductor the grid of said device,

means for causing said outer conductor to emit electrons at a pointthereon removed from said one end of said transmission line, and anoutput circuit coupled to said grid.

7. An ultrashort wave oscillation generator circuit comprising amulti-electrode electron discharge device having within its envelope anoscillatory circuitformed of a concentric transmission line having innerand outer conductors capacitively coupled together at one of their ends,said inner conductor comprising a perforated grid and said outerconductor comprising a cathode arranged to emit electrons at the endopposite said one end of said line, means for applying a high positivepotential to said grid relative to said cathode, and means for producinga uniform magnetic field in the length of said transmission line.

8. A circuit in accordance with claim 7, characterized in this that saidmeans for producing said field comprise a coil surrounding said envelopefor producing a constant magnetic field, and a magnet yoke having poleson opposite sides of said envelope, said inner conductor of saidtransmission line being made of a magnetic material.

9. An oscillation generator circuit comprising an electron dischargedevice having a pair of electrodes in the form of inner and outerconcentric conductors having substantially uniformly distributedinductance and capacitance, said outer conductor being substantially anintegral multiple including unity of one-quarter of the length of theoperating wave and being an emitter of electrons in the form of acylinder, means for maintaining said inner conductor at a positivepotential relative to said outer conductor whereby said inner conductoris a collector of electrons, means for producing a constant magneticfield Within the lengths of said concentric conductors, and autilization circuit directly connected to said inner conductor at apotential nodal point thereon.

10. An ultrashort wave oscillation generator circuit comprising amulti-electrode electron discharge device having within its envelope anoscillatory circuit in the form of a con centric transmission linehaving inner and outer conductors substantially one-quarter of thelength of the operating wave, said conductors comprising electrodes ofsaid device, said inner conductor comprising a perforated grid over atleast a portion of its length, means for applying suitable polarizingpotentials to said electrodes, said outer conductor comprising anemitter of electrons.

HAROLD OLAF PETERSON.

